Lovibond Maxi Direct, Instruction Manual, Page: 107 / 268

105
MaxiDirect_2c 03/2010
1.1 Methods
Notes:
Digestion procedure for the determination of total dissolved and undissolved iron.
1. Add 1 ml of concentrated sulfuric acid to 100 ml water sample. Heat and boil for 10
minutes or until all particles are dissolved. After cooling down, the sample is set to a
pH-value of 3 to 6 by using ammonia solution. Refill with deionised water to the
previous volume of 100 ml and mix well. 10 ml of this pre-treated solution is used for
the following analysis. Perform as described by the selected test method.
2. Water which has been treated with organic compounds like corrosion inhibitors must
be oxidised where necessary to break down the iron. Therefore add 1 ml concentrated
sulfuric acid and 1 ml concentrated nitric acid to 100 ml water sample and boil to
approx. half volume. After cooling down, proceed as described above.
result B result A
minus
= Fe
3+
Fe
2+
+ Fe
3+
Fe
2+
Fe
2+
+ Fe
3+
IRON LR
tablet
IRON (II) LR
tablet
methods
220, 222, 223
dissolved Iron
dissolved and
undissolved Iron
Filtration Digestion
Iron Determination